(a) Field of the Invention
The present invention relates to a rotary bearing assembly used mainly with a two-spindle, centrally pressing type top roller used in the draft part of a spinning machine. Not only is it concerned with a bearing construction for a pressing top roller used in the draft part of a textile machine, such as a spinning machine, but broadly it is also concerned with a rotary bearing assembly of the sealed type generally used in the field of textile machinery and in other similar fields.
(B) Description of the Prior Art
The leakage of lubricating oil (including grease) enclosed in the bearing part of a conventional rotary wheel not only shortens the period for replenishing the lubricating oil and complicates the maintenance but also shortens the life of the bearing and forms a major cause of damage and seizure.
In the case of textile machinery, besides the above, said leakage causes other undesirable phenomena including the entry of dust and the rolling-in or twining of fly, which entails the fouling of the product and the formation of knob yarn. As a result, the vicious circle of sucking-out of oil by fly.fwdarw.running short of oil.fwdarw.seizure can hardly be cut off. Generally, as a measure therefor, it is usual practice to provide oil seals. However, so long as pressing top rollers used in textile machinery are concerned, the measure using oil seals has the disadvantage of fibers entering the seals under the action peculiar to fly, often making impossible the cell rotation of the top rollers. Therefore, the labor cost and time loss incurred in cleaning and oiling heretofore periodically performed are very high.
Accordingly, the development of a high performance top roller which requires no maintenance is one of the important needs long pending among engineers concerned.